const express = require('express')
const router = express.Router()
const { Category, Course } = require('../../models')
const { Op } = require('sequelize')
const { NotFoundError } = require('../../utils/errors')
const { success, failure } = require('../../utils/responses')

/**
 * 查询分类列表
 * GET /admin/categories
 */
router.get('/', async function (req, res) {
  try {
    // 查询参数
    const query = req.query
    // 分页
    const pageSize = Math.abs(Number(query.pageSize)) || 10
    const currentPage = Math.abs(Number(query.currentPage)) || 1
    const offset = (currentPage - 1) * pageSize
    // 查询条件
    const condition = {
      order: [
        ['rank', 'ASC'],
        ['id', 'ASC'],
      ],
      limit: pageSize,
      offset,
    }
    // 模糊查询
    if (query.name) {
      condition.where = {
        name: {
          [Op.like]: `%${query.name}%`,
        },
      }
    }
    // 查询
    const { count, rows } = await Category.findAndCountAll(condition)
    success(res, '查询分类列表成功', {
      categories: rows,
      pagination: {
        total: count,
        pageSize,
        currentPage,
      },
    })
  } catch (error) {
    failure(res, error)
  }
})

/**
 * 查询分类详情
 * GET /admin/categories/:id
 */
router.get('/:id', async function (req, res) {
  try {
    const category = await getCategory(req)
    success(res, '查询分类详情成功', { category })
  } catch (error) {
    failure(res, error)
  }
})

// 创建分类
router.post('/', async function (req, res) {
  try {
    const body = filterBody(req)
    const newCategory = await Category.create(body)
    success(res, '创建分类成功', { newCategory }, 201)
  } catch (error) {
    failure(res, error)
  }
})

// 更新分类
router.put('/:id', async function (req, res) {
  try {
    const body = filterBody(req)
    const category = await getCategory(req)
    category.update(body)
    success(res, '更新分类成功', { category })
  } catch (error) {
    failure(res, error)
  }
})

// 删除分类
router.delete('/:id', async function (req, res) {
  try {
    const category = await getCategory(req)
    const count = await Course.count({ where: { categoryId: req.params.id } })
    if (count > 0) {
      throw new Error('分类下有课程，请先删除课程')
    }
    await category.destroy()
    success(res, '删除分类成功')
  } catch (error) {
    failure(res, error)
  }
})

/**
 * 公共方法: 查询当前分类
 */
async function getCategory(req) {
  const { id } = req.params
  const condition = {
    include: [
      {
        model: Course,
        as: 'courses',
      },
    ],
  }
  const category = await Category.findByPk(id, condition)
  if (!category) {
    throw new NotFoundError(`ID：${id} 分类不存在`)
  }
  return category
}

/**
 * 公共方法：白名单过滤
 * @param req
 * @returns {{name, rank: *}}
 */
function filterBody(req) {
  return {
    name: req.body.name,
    rank: req.body.rank,
  }
}

module.exports = router
